1. Technical Field
The present disclosure generally relates to information handling systems and in particular to controlling redundant power supplies in an information handling system.
2. Description of the Related Art
As the value and use of information continue to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes, thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
An information handling system may include a number of redundant alternating current to direct current (AC-DC) or direct current to direct current (DC-DC) power supplies that provide regulated voltages to different loads. The load current may vary across a broad range from relatively high peak currents to very low stable currents. The AC-DC and DC-DC power supplies used in servers typically should be designed for a large range of server configurations and generally need to be designed to handle the full load of the server safely, and also need to be optimized for efficiency, size, and cost.
Most redundant power solutions require a level of load or power sharing between the individual power supplies. To ensure that availability and redundancy of the power supplies are maintained, the sharing solution requires load balance accuracy, as well as a high degree of stability. One method of power sharing uses an active current sharing method that includes a common share bus that is connected to all of the power supplies. The stability of the active current sharing method depends on each power supply's output impedance, the intermediate impedance between the power supplies, and the compatibility between different power supply designs.
The active current sharing method can use a methodology commonly termed as “Master-Slave”. The master power supply determines the voltage on the common share bus which is proportional to its own output current. The slave power supplies attempt to follow the master output current by reading the common share bus voltage. Under conditions, in which the power supplies share a common output rail and have limited design margin, an oscillatory behavior can be observed. Unfortunately, the oscillating behavior between the power supplies can result in an increase in output voltage, which is referred to as “voltage walking”, which results from a master-slave power supply role change, and causes loss of current sharing.